SOMMERFELD EFFECT IN NON-IDEAL VIBRATION SYSTEMS DRIVEN BY MOTORS

The motor output power of a real rotor system is limited and cannot provide ideal constant drive force. As the input voltage value of the motor increases, there will be long-term average rotor speed stagnation and the steady-state response of the system appears multiple values and switches by sudden jumps around the natural frequency of the system, which is called "Sommerfeld effect". This kind of non-ideal motor will pass through the Sommerfeld effect zone when starting, and the motor speed will fluctuate sharply when it is trapped in this Sommerfeld zone for a long time, which will seriously affect the performance life of the motor. The theoretical simplification ignores the speed fluctuation and focuses on the steady-state average speed, and cannot observe the internal energy change of the system. Therefore, the interaction process of the motor system and the vibration system is studied by means of numerical analysis method. The electromechanical coupling dynamic model of the non-ideal DC motor, mass and unbalanced rotor system is established. The change law of each internal force component of the vibration system is analyzed by Matlab/Simulink modeling, and the generation, evolution and disappearance process of Sommerfield effect are investigated. It is observed that when the non-ideal system enters the resonance region, the restoring force, inertia force and damping force will suddenly produce an even fold frequency component, resulting in the phenomenon of fast rotation, stop rotation and even reversal of the system under the premise that the rotor average speed is gradually consistent with the natural frequency of the system, and the jump ends when the input voltage value is greater than the critical voltage value. The study describes many nonlinear behaviors due to the non-ideal drive system, and finally provides some guidance for the dynamic design of the vibration system and ensures the normal operation of the power.